The invention relates to a device for measuring and metering the electrical energy consumed by an installation, a device comprising means for measuring the currents consumed by the installation, means for measuring the associated voltages applied to the installation, and a standard electrical energy meter operating in AC and comprising current and voltage inputs.
Standard electrical energy meters operate in AC, typically at 50 or 60 Hz. They cannot be used directly for metering the electrical energy consumed by an installation supplied with DC or with AC of a frequency, for example 400 Hz, different from that for which the standard AC meter is designed.
In certain electrical energy distribution systems, it has been proposed (EP-A-550348) to supply the users from a DC energy distribution bus, the DC being obtained from the AC energy system by means of a central AC/DC conversion module. Naturally, energy metering can be performed upstream from the central module by means of a standard AC meter. However, when the installations supplied by the bus are independent and correspond to different users, it is preferable to have electrical energy metering devices associated with each of the installations. These devices must operate in DC and be homologated and qualified by electrical energy distributors and by qualification authorities to be able to be used for rating and billing the energy consumed.
Although fully electronic devices for metering electrical energy exist enabling a energy measurement to be made, either in DC or in AC, these devices are not at present homologated or have to follow a very long qualification cycle, so that they cannot be used in the short term for billing the energy consumed.